Microswitch-actuated control units are currently based on the concept of mounting the or each cam fixedly on a rotatable shaft to actuate a microswitch the position of which is adjustable to vary the switch point. The rotatable shaft has an associated quadrant with a graduated scale marked thereon, against which the actuation position of the microswitches may be read.
This type of construction, with adjustable microswitches, involves a very bulky structure the complexity of which becomes even greater with an increase in the number of microswitches utilised, and it will be appreciated that each microswitch can operate on only a single parameter so apparatus having several microswitches is very often required. However, with the structures of the known type there are considerable limitations in relation to the number of microswitches which can be used, in that the known structures involve an excessive complexity and bulk if more than a very limited number of microswitches are employed.